Sure, you can make reasonably convincing arguments that Republicans will retain control of both chambers. But you can also make reasonably convincing arguments that Democrats will pick up the necessary 15 seats in the House or six in the Senate -- or both.
Any way you look at it, control of the House is a very close call. Although control of the Senate isn't quite as close, Republicans are no sure bet to keep their majority for another two years.
At different times in recent months, Republicans and Democrats each seemed to have the advantage in terms of winning the House, only to see the momentum shift the other way. In the Senate campaigns, the story has been more about an expansion in the number of potentially competitive races, and thus a wider range of possible outcomes.
For example, Senate Republicans Jon Kyl in Arizona and (Democrats would argue) George Allen in Virginia are seen as facing more competitive challenges than anyone thought six months ago. But so is Democrat Maria Cantwell in Washington state.
For that matter, while the political environment in the country obviously favors Democrats, and while Democrats have surged in recent years in the Northeast in general and in New Jersey in particular, the Senate race in the Garden State between appointed Democrat Robert Menendez and Republican state Sen. Tom Kean Jr. has remained stubbornly close.
The recent six-day shutdown of the state government -- the result of a stalemate between a Democratic governor and a Democratic-controlled Legislature -- has created a short-term bump in the road for Menendez that prevents him from taking advantage of the longer-term favorable trends for his party and from building a strong lead over Kean.
Although some of the ups and downs in the House and Senate campaigns are unique to specific races, more is going on here. Some of the changing fortunes are undoubtedly affected by shifting national trends, specifically President Bush's popularity. We have had at least two, and probably three, shifts in momentum in the past eight months.
From mid-December until late February, Bush had job-approval ratings of 40 to 49 percent in 27 out of 31 major national polls cited on PollingReport.com. While those aren't exactly good numbers, they were an improvement from November, when he had been in the 30s.
Then, starting in the last few days of February, the president's plunge began. From then until the second week of June, 50 out of 51 major national polls showed his approval rating in the 30s. During this free fall, GOP hopes of retaining the House began to fade. From the second week of June until the second week of July, however, Bush's approval numbers hovered around 40 percent; five out of 10 polls showed him just above 40, the other five just below. During this period, Republicans breathed a little easier. At least from the macro-political perspective, things looked less like the apocalypse, or in the words of one of the GOP's best pollsters, "less worse" than before.
Starting in mid-July, we have begun to see a new trend, with five major national polls in a row, and six out of the last seven, showing the president's approval ratings back under 40 percent, with three at 37 percent or lower. It is too soon to say whether this is the beginning of a strong downward trend or simply a small decline to a new plateau for Bush.
The operative point is that there is, and will likely remain, an enormous amount of uncertainty over this midterm election. This is a campaign with hundreds of moving parts.
While the outcome may look painfully obvious in retrospect, it's far from clear now. In both parties, it seems that the more experienced the political operative, the more doubt he or she has about what will transpire on Election Day. And that feeling may not change between now and November 7.